[roll] Roll fuchsia [async-utils] Add delayed behavior to HangingGet

This change adds a new constructor for HangingGet that does not take an
initial state. In this case, Subscriber's do not get notified of the
initial state until the first time a publisher sets or updates the
state.

Test: fx test -o async-utils-tests, manuall on astro, follow-up CL
Original-Bug: 127822
Original-Reviewed-on: https://fuchsia-review.googlesource.com/c/fuchsia/+/862019
Original-Revision: d43b258372eff7de1569e2b0c104d317ca110b6e
GitOrigin-RevId: 330905e97350b0f24ed3100967d40ea8506edf1b
Change-Id: Ia87d9945221703a0e82a9717c5d5aba170dd1083
diff --git a/stem b/stem
index 1c37602..f77c7d7 100644
--- a/stem
+++ b/stem
@@ -11,7 +11,7 @@
              githooks="integration/git-hooks"
              remote="https://fuchsia.googlesource.com/fuchsia"
              gerrithost="https://fuchsia-review.googlesource.com"
-             revision="f3926c99d9969c82174c141257e8237b5345045c"/>
+             revision="d43b258372eff7de1569e2b0c104d317ca110b6e"/>
   </projects>
   <hooks>
     <hook name="install-environment"